Interesting to consider in light of the Bama job opening up.. Lot of factors go into it, including intangibles, environment, expectations, resources, recruiting base et al. I would rank my top 20 as:
1. Texas
2. Georgia
3. USC
4. Bama
5. OSU
6. Michigan
7. ND
8. Florida
9. PSU
10. A&M
11. Nebraska.
12. Oregon
13. Oklahoma
14 LSU. I only rate it this low because you'd have to live in Louisiana.
15. FSU
16. Virginia Tech
17. Arkansas
18. Michigan St.
19. Wisconsin
20. N. Carolina
21. Washington
Others: Miami, BYU
Edit: I left out Auburn. I'd have them in the 12-15 range.
Edit #2: I left out Tennessee & Clemson. I'd have Tennessee just behind Florida and ahead of PSU; I'd have Clemson just behind FSU and just ahead of VT. And I think the points made about UCLA are pretty valid. Lets put then in just behind Arkansas and just ahead of MSU.
One thing to remember about UCLA, Oregon, and Washington. They're in the BT, but only at 1/2 (or so) rates for the first 6(?) years, So that's a similar problem to the ACC teams, except they can recruit as a BT team.